Input to the timerclk on the MPC8280

annamaya annamaya at
Thu Jan 20 09:08:18 EST 2005

I've asked this question on this forum before but it
did not get answered. I tried asking the same question
in the U-Boot forum with no results. So, I am going to
try this again.

According to section 4.1.2 on Page 4-4 in the MPC8280
User's Manual, one should be able to use a combination
of  external clocks on Port C pins 25, 26, 27 and 29,
the CPM cloak and BRG1 to generate a 32KHz or a 4MHz
clock. I am unable to find  any code in u-boot or any
other place that initializes any of these pins to be
external clocks. And as for BRG1, I believe it is
being used for the SMC clock.

I am unable to understand how this is done. Can we
have a timerclk input WITHOUT an external clock
signal? Can I just use the CPM clock to generate this?
How is this being done in U-Boot now?

Thanks much for your help. I really need an answer to

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